Method and apparatus for revitalizing plasma processing tools

ABSTRACT

Methods for revitalizing components of a plasma processing apparatus that includes a sensor for detecting a thickness or roughness of a peeling weakness layer on a protective surface coating of a plasma processing tool and/or for detecting airborne contaminants generated by such peeling weakness layer. The method includes detecting detrimental amounts of peeling weakness layer buildup or airborne concentration of atoms or molecules from the peeling weakness layer, and initiating a revitalization process that bead beats the peeling weakness layer to remove it from the component while maintaining the integrity of the protective surface coating.

BACKGROUND

Aluminum-based parts are widely used in semiconductor manufacturingprocesses that employ plasma. Surface coatings of the aluminum-basedparts are very critical in high-density plasma processes, such as plasmaetching, because the plasma process includes highly reactive andcorrosive gas. Very often, the plasma process is sensitive to changes insurface coatings of the aluminum-based and similar parts, including fineceramic (FC) parts. Accordingly, maintaining a clean and stable surfacecoating is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features have beenarbitrarily increased or reduced for clarity of discussion.

FIG. 1 shows a schematic view of a semiconductor wafer processing systemin accordance with some embodiments.

FIG. 2 is a diagram of a plasma chamber according to some embodiments.

FIG. 3 and FIG. 4 are diagrams of a controller in accordance with someembodiments.

FIG. 5 depicts plasma impact on a coating of plasma processing toolsaccording to some embodiments.

FIG. 6 depicts a peeling weakness surface (PWS) on a surface coatingaccording to some embodiments.

FIG. 7 depicts charts of contaminant concentration over time accordingto some embodiments.

FIG. 8 illustrates the effects of a cleaning process according to someembodiments.

FIG. 9 illustrates the difference between a wet clean process and a beadbeating clean process according to some embodiments.

FIG. 10 is a chart illustrating the PWS before and after cleaningaccording to some embodiments.

FIG. 11 is a second chart illustrating the PWS after cleaning andcontinued use according to some embodiments.

FIG. 12 depicts charts of coating thickness and roughness according tosome embodiments.

FIG. 13 is a flowchart of a process for detecting a PWS condition andinitiating a cleaning process in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows includes embodiments in which the first and second features areformed in direct contact, and also includes embodiments in whichadditional features are formed between the first and second features,such that the first and second features are not in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus/device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein may likewise be interpreted accordingly. In addition, theterm “made of” may mean either “comprising” or “consisting of” In thepresent disclosure, a phrase “one of A, B and C” means “A, B and/or C”(A, B, C, A and B, A and C, B and C, or A, B and C), and does not meanone element from A, one element from B and one element from C, unlessotherwise described.

In plasma etching and/or deposition processes, contaminant particlesreduce the yield of the processes by, for example, undesirably shieldingportions of a mask pattern or contaminating a workpiece. In some plasmaprocess apparatuses having a chamber made of aluminum, a surface coatingis employed to prevent particles from being generated. Some surfacecoatings of the aluminum-based and FC parts, such as yttrium-basedceramics or coatings, make it possible to extend operational time,compared to others, such as anodized aluminum (Al) alone. Also, somesurface coatings of the aluminum-based parts generate contaminantparticles more easily than others. The surface change of thealuminum-based part's coatings over time adversely affects the radiofrequency (RF) current return of wafer stages, as well as plasmacharacteristics including radical concentrations, plasma density andother parameters, which in turn detrimentally causes significant etchrate drift and the like. It is therefore desirable to maintain a cleanand a stable surface in locations and routes where wafers and othertools pass through during the plasma process, such as tool grippers,chambers, substrate holders, and the like. In particular, the ability toproduce high quality microelectronic devices and reduce yield losses isdependent upon maintaining the surfaces of critical componentssubstantially defect-free. This would include maintaining the surfacesfree of particulate matter, e.g., maintaining an ultra-clean surface,thereby ensuring that particulate matter is not deposited on the surfaceof the wafer, the reticle or mask, or other critical components. This isof particular concern as finer features are required on themicroelectronic device. The types of particulate matter are anyarbitrary combination depending on the environment and the vacuumcondition of the plasma apparatus employed. The particulate matter isintroduced from etching byproducts in the semiconductor manufacturingprocess, organic hydrocarbon contaminants, any kind of fall-on dust,outgassing from coatings, and the like.

Previously, plasma process equipment has been cleaned using a vacuum andan isopropyl alcohol/ethanol wipe-down after removal from the processingapparatus. In other instances, a wet clean process is employed. Particlecounters are then used to monitor and verify cleanliness. However, suchmanual and wet cleaning operations are not preferable for certaindelicate or small components. For purposes of cleaning a peelingweakness surface (PWS) layer that builds up on protective coatings ofplasma processing tools, such as wafer holding tools as describedherein, it has been discovered that manual and wet clean processes aresimply not effective in removing the PWS layer. Plasma processing toolswill then eventually contaminate the other semiconductor waferprocessing apparatus over time during operational use. Thus, alternatemethods of maintaining cleanliness of plasma-exposed components isrequired.

FIG. 1 is a schematic view of a semiconductor wafer processing system100 in accordance with various embodiments. In some embodiments, thesemiconductor wafer processing system 100 includes an etch system, suchas a plasma etching system. The processing system 100 comprises, invarious embodiments, a plasma processing chamber 120 for etching asubstrate 116, and at least one chamber surface 108 including a surfacecoating 132 having an yttrium compound, such as Y_(x)O_(y)F_(z) or YF₃.The substrate 116 is disposed on an electrostatic chuck (ESC) 112 insidethe semiconductor wafer processing system 100. Coupled to the plasmaprocessing chamber 120 are a radio frequency (RF) or microwave powersource 124 and a low pressure vacuum system 128. The RF or microwavepower generator 124 provides power to create a plasma 136 inside theplasma processing chamber 120. Direct current (DC) power is used inaddition to or in place of the RF or microwave sources. Process gas 140is introduced into the plasma processing chamber 120 to create theplasma 136. Process gases 140 include oxygen-containing gases such asO₂, CO, CO₂, H₂O or H₂O₂. Process gases also include gasses such as CF₄,C₄F₈, C₅F₈, F₂, SF₆, HBr, NH₃, NF₃, H₂, HCl, Cl₂ and others in variousembodiments.

It should be appreciated that while the processing system 100 isdescribed herein as a plasma etching system, the embodiments of thedisclosure should not be limited thereto. The processing apparatus 100is configured to perform any manufacturing procedure on a semiconductorwafer, such as substrate 116. For example, the processing apparatus 100is configured to perform manufacturing procedures that includedeposition processes such as plasma-enhanced chemical vapor deposition(PECVD), sputtering, and/or other deposition processes. Alternately,processing system 100 includes a cleaning system, a developing system, achemical treatment system, a thermal processing system, a coatingsystem, a chemical vapor deposition (CVD) system, a physical vapordeposition (PVD) system, an ionized physical vapor deposition system(i-PVD), an atomic layer deposition (ALD) system, and/or combinationsthereof. The disclosures herein are not limited to such devices andinclude, thermal process devices, cleaning apparatus, testing apparatus,or any other procedure involved in the processing of the semiconductorwafers, and/or any combination of such procedures.

Turning now to FIG. 2, therein is depicted exemplary internal componentsof a semiconductor wafer processing system 100, which will now bedescribed in more detail. Processing system 100 includes elements forcontrolling the chamber wall temperature. As shown, a wall temperaturecontrol element 266 is coupled to a wall temperature control unit 265,and the wall temperature control element 266 is coupled to theprocessing chamber 120. The temperature control element includes aheater element, cooling element and/or temperature sensing element. Forexample, the heater element includes a resistance heater or a carbonheater element. The temperature of the processing chamber 120 ismonitored using a temperature-sensing device such as a thermocouple.Furthermore, a chamber temperature controller (not shown) utilizes thetemperature measurement as feedback to the wall temperature control unit265 in order to control the temperature of the processing chamber 120.In additional embodiments, the substrate holder 240 includes temperaturecontrol elements 260 for controlling the temperature of the substrate116. Control/power source 262 provides signals and/or energy to thecontrol elements 260, and heat or cool the substrate holder 240 and thesubstrate 116. In addition, the processing system 100 further includes apressure control system 250 coupled to the processing chamber 120 tocontrol the pressure in the processing chamber 120. The pressure controlsystem 250, in various embodiments, is a vacuum pump 128 with a gatevalve 254 for controlling the chamber pressure, and a pressure sensor(not shown). For example, the vacuum pump 128 is capable of a pumpingspeed up to five thousand liters per minute. Vacuum pumps 128 are usefulfor low pressure processing, typically less than 50 mTorr. For highpressure (i.e., greater than 100 mTorr) or low throughput processing(i.e., no gas flow), a mechanical booster pump and dry roughing pump isused. Although the pressure control system 250 is shown coupled to thebottom of the processing chamber 120, this is not required. In alternateembodiments, a pressure control system 250 is coupled to the top, and/orside of the processing chamber 120. Furthermore, a controller 300(described below with respect to FIG. 3) utilizes a pressure measurementas feedback to the pressure control system 250 in order to control thepressure of the plasma processing chamber 120. The processing chamber120 facilitates the formation of processing plasma 136 in a processspace adjacent to substrate 116. Alternately, the plasma processingchamber 120 facilitates the introduction of a process gas 140 in aprocess space adjacent to substrate 116. The processing system 100 isconfigured to process two or three hundred millimeter (mm) substrates,or larger substrates. In an alternate embodiment, processing system 100includes multiple processing chambers 120, and the processing system 100operates by generating plasma 136 in one or more processing chambers120.

In various embodiments, the processing system 100 further includes anupper assembly 220 coupled to the processing chamber 120. For example,the upper assembly 220 includes a gas distribution plate 275 that iscoupled to a gas distribution system 270 for introducing a process gas140 into a process space within the processing chamber 120 in someembodiments. The gas distribution plate 275 further comprises aplurality of orifices 276 configured to distribute one or more gassesfrom the gas distribution system 270 to the process space of theprocessing chamber 120. The process gas 140 includes at least one ofNH₃, HF, H₂, O₂, CO, CO₂, Ar, He, and N₂. For example, during a polyand/or nitride processes the process gas 140 is at least one ofdichlorosilane (DCS), trichlorosilane (TCS), SiH₄, Si₂H₆,hexachlorodisilane (HCD), and NH₃ in some embodiments. During a CVDoxide process, the process gas 140 includes at least one oftetraethoxysilane (TEOS) and bistertiarybutylaminosilane (BTBAS). Duringan ALD process the process gas 140 includes at least one of H₂O,trimethylaluminum (TMA), hafnium tertbutoxide (HTB), NO, or N₂O. Duringa metal CVD process the process gas 140 includes at least one oftungsten carbonyl, rhenium carbonyl, andt-amylimidotris(dimethylamido)tantalum(V) (taimata) in some embodiments.

In various embodiments, the upper assembly 220 is configured to performat least one of the following functions: provide a capacitively coupledplasma (CCP) source, provide an inductively coupled plasma (ICP) source,provide a transformer-coupled plasma (TCP) source, provide a microwavepowered plasma source, provide an electron cyclotron resonance (ECR)plasma source, and provide a surface wave plasma source.

In various embodiments, the upper assembly 220 includes an upperelectrode 230 and/or magnet system components (not shown). In someembodiments, the upper assembly 220 includes supply lines, injectiondevices, and/or other gas supply system components (not shown).Furthermore, the upper assembly 220 includes a housing, a cover, sealingdevices, and/or other mechanical components (not shown).

As shown in FIG. 2, the processing system 100, in various embodiments,further includes an inner deposition shield 229, a shutter 231, an innershutter 232, a bottom cover 233, an exhaust plate 234, and a lower wallcover 235. In various embodiments, the inner deposition shield 229, theshutter 231, the inner shutter 232, the bottom cover 233, the exhaustplate 234, the lower wall cover 235, and/or the substrate holder 240include a protective barrier or surface coating 132 formed on one ormore exposed surfaces to prolong life and prevent decay of thecomponents due to plasma exposure.

In various embodiments, the processing chamber 120 includes a monitoringdevice 215 connected to a monitoring port (not shown), in order topermit optical or sensor monitoring of the plasma processing chamber 120and used for end point detection, contamination detection and or otheralerting of process operations.

In various embodiments, the substrate 116 is transferred into and out ofthe processing chamber 120 through an opening 294 that is controlled bya gate valve assembly 290. In addition, the substrate 116 is transferredon and off the substrate holder using a robotic substrate transfersystem (not shown). In addition, the substrate 116 is received bysubstrate lift pins (not shown) housed within the substrate holder 240and mechanically translated by devices housed therein. Once thesubstrate 116 is received from substrate transfer system, it is loweredto an upper surface of substrate holder 240.

In some embodiments, the substrate 116 is affixed to the substrateholder 240 via an electrostatic clamping system, but passive waferrestraints are also used. Moreover, the process gas 140 is delivered tothe backside of the substrate 116 via a backside gas system (not shown)to improve the gas-gap thermal conductance between the substrate 116 andthe substrate holder 240. Such a system is utilized when temperaturecontrol of the substrate 116 is required at elevated or reducedtemperatures. In other embodiments, heating elements, such as resistiveheating elements, or thermoelectric heaters/coolers are included.

In alternate embodiments, wafer holding tools such as a substrate holder240, further include a vertical translation device (not shown) that issurrounded by a bellows (not shown) coupled to the substrate holder 240and the processing chamber 120, which is configured to seal the verticaltranslation device from the reduced pressure atmosphere in theprocessing chamber 120. Additionally, a bellows shield (not shown) iscoupled to the substrate holder 240 and configured to protect thebellows.

As shown in FIG. 2, the substrate holder 240, for example, furtherincludes a focus ring 241, a focus ring base 242, an ESC enclosure 243,an insulator ring 244, an electrostatic chuck 112, and a lower electrode247. The focus ring 241, the focus ring base 242, the ESC enclosure 243,and/or the insulator ring 244, in various embodiments, include a surfacecoating or protective barrier (not shown) formed on one or more exposedsurfaces to prolong life and prevent decay of the components due toplasma. Alternatively, the substrate holder 240 is configured in any ofa variety of known manners.

In various embodiments, the substrate holder 240 includes a lowerelectrode 247 through which RF power is coupled to the process gas 140in the process space of the plasma processing chamber 120. For example,substrate holder 240 is electrically biased at an RF voltage via thetransmission of RF power from, for example, a first RF or microwavesource 124. In some cases, an RF bias is used to heat electrons to formand maintain the plasma 136. A frequency for the RF bias ranges from onemegahertz (MHz) to one hundred MHz in some embodiments, for example,13.56 MHz. In addition, in other embodiments, the substrate holder 240includes a surface coating 132 (i.e., a protective barrier) formed onone or more exposed surfaces of the substrate holder 240.

Again referring to FIG. 2, some embodiments of the upper assembly 220include an upper electrode body 221, a top baffle assembly 222, atemperature control plate 223, an electrode cover 224, an inner shieldring 225, and an outer shield ring 226. In various embodiments, theelectrode cover 224, the inner shield ring 225, and the outer shieldring 226 include a surface coating or protective barrier (not shown)formed on one or more exposed surfaces. In alternate embodiments, aprotective barrier (not shown) is formed on one or more interiorsurfaces of the upper assembly 220.

In various embodiments, the processing system 100 includes a second RFsystem 285 that is coupled to the upper electrode 221 and used toprovide additional RF power to the process gas 140 in the process spaceof the plasma processing chamber 120. In various embodiments, the upperelectrode 221 is electrically biased at an RF voltage via thetransmission of RF power from the second RF system 285. In some cases,this RF signal is used to form and/or control plasma. The frequency forthe second RF system 285 ranges from one MHz to one hundred MHz, forexample, 60 MHz.

Protective barriers, when used to protect components in processingsystem 100, are created in a number of different ways. In one case, aprotective barrier is created by anodizing a metal, and impregnating theanodized surface with a fluoropolymer, such as polytetrafluoroethylene(PTFE). For example, a protective barrier is formed by hard anodizingaluminum or hard anodizing an aluminum alloy and impregnating thehard-anodized surface with PTFE. In other cases, a protective barrier iscreated using at least one of Al₂O₃, yttria (Y₂O₃), Sc₂O₃, Sc₂F₃, YF₃,La₂O₃, CeO₂, Eu₂O₃, and DyO₃. In addition, a protective barrier is atleast one of a Group III element (Group III of the periodic table) and alanthanide element; the Group III element includes at least one ofyttrium, scandium, and lanthanum in some embodiments. The lanthanideelement includes at least one of cerium, dysprosium, and europium insome embodiments. In some embodiments, a protective barrier is formed inthe processing chamber 120 as part of a pre-process coating, such as asilicon nitride or Si coating before forming the desired process film.In some embodiments, a sensor 299, such as an x-ray photoelectronspectrometer (XPS) is provided within the plasma processing chamber 120,or in operable proximity thereto, to monitor the level of contaminantson FC parts, plasma processing parts or tools or otherwise inside thechamber (i.e., airborne contaminants). The sensor 299 senses spectracorresponding to yttrium-based compounds or other pertinent contaminantsthat are generated by the plasma processing parts and tools over timedue to plasma exposure.

As shown in FIG. 2, a processing module 100 includes an upper assembly220 and a processing chamber 120 having a substantially cylindricalelectrically conductive unit including an open top in variousembodiments. The upper assembly 220 is detachably fixed to theprocessing chamber assembly 120 by a locking mechanism 205, and thus,the processing chamber assembly 120 is opened and/or closed freely. Thisfacilitates the replacement or cleaning of components and/or thecleaning of the chamber.

A gas supply system 270 is coupled to the upper assembly 220. In someembodiments, a two-zone gas distribution configuration is used. A firstgas supply line 271 is coupled to a first distribution zone (not shown),and a second gas supply line 272 is coupled to a second distributionzone (not shown). For example, the first distribution zone is located ina center portion of the chamber, and the second distribution zone islocated in a peripheral portion of the chamber. A plurality of gasoutlet holes 276 are formed in the upper assembly 220 to provide aprocess gas into a plasma processing space 212. The outlet holes(orifices) 276 are connected to the gas supply system 270 through thebaffle 222. Thus, one or more different process gasses are supplied fromthe gas supply source 270 at different rates into different zones of theplasma processing space 212 via the outlet holes 276.

In various embodiments, an exhaust plate 234 is provided around thebottom portion of the substrate holder 220. The exhaust plate 234 isused to separate the plasma processing space 202 from an evacuationspace 204, and the exhaust plate 234 includes a plurality of holes 239formed in the exhaust plate 234. For example, the plurality of holes 239include a plurality of through holes and a plurality of blind holes(non-through holes). The plasma processing space above the exhaust plate234 and the evacuation space 204 below the exhaust plate 234 communicatewith each other through the through holes 239. Thus, the process gas 140inside the plasma processing chamber 120 travels through the throughholes 239 in the exhaust plate 234 and is then evacuated as necessary bythe pressure control system 250.

The system of FIG. 2 is used for etching, for example, a gate stack fora semiconductor device. Specifically, a gate stack originates from amultilayer structure including a layer of undoped polysilicon, a layerof doped polysilicon, and an antireflective coating layer. Thismultilayer structure is then masked and etched to provide a gate stackstructure having desired critical dimensions, such as a vertical heightcritical dimension (CD). Other semiconductor devices are readilycontemplated as well.

Over time, the repeated performance of etching processes leads toconditions within the processing chamber 120 that are undesirable forfurther performance of the etched process. For example, the etchingprocess leads to particle buildup on chamber components, which breakaway to contaminate the substrate 116 being processed. Thus, periodiccleaning of the plasma processing chamber 120 must be performed.

FIG. 3 and FIG. 4 illustrate a computer system 300 for controlling theprocessing system 100 and its components in accordance with someembodiments of the present disclosure. FIG. 3 is a schematic view of acomputer system 300 that controls the plasma processing system 100 ofFIG. 1. In some embodiments, the computer system 300 is programmed toinitiate a process for monitoring contamination levels of chambercomponents, wafer holding tools or airborne contamination arising fromthe same and provide an alert that cleaning is required. In someembodiments, manufacturing of semi-conductor devices is halted inresponse to such an alarm. In some embodiments, a clean in place (CIP)process is initiated in response to the activation of such an alarm. Asshown in FIG. 3, the computer system 300 is provided with a computer 301including an optical disk read only memory (e.g., CD-ROM or DVD-ROM)drive 305 and a magnetic disk drive 306, a keyboard 302, a mouse 303 (orother similar input device), and a monitor 304.

FIG. 4 is a diagram showing an internal configuration of the computersystem 300. In FIG. 4, the computer 301 is provided with, in addition tothe optical disk drive 305 and the magnetic disk drive 306, one or moreprocessors 311, such as a micro-processor unit (MPU) or a centralprocessing unit (CPU); a read-only memory (ROM) 312 in which a programsuch as a boot up program is stored; a random access memory (RAM) 313that is connected to the processors 311 and in which a command of anapplication program is temporarily stored, and a temporary electronicstorage area is provided; a hard disk 314 in which an applicationprogram, an operating system program, and data are stored; and a datacommunication bus 315 that connects the processors 311, the ROM 312, andthe like. Note that the computer 301, in some embodiments, includes anetwork card (not shown) for providing a connection to a computernetwork such as a local area network (LAN), wide area network (WAN) orany other useful computer network for communicating data used by thecomputer system 300 and the plasma processing system 100.

The program for causing the computer system 300 to execute the processfor controlling the plasma processing system 100 of FIG. 1, andcomponents thereof and/or to execute the process for the method ofmanufacturing a semiconductor device according to the embodimentsdisclosed herein are stored in an optical disk 321 or a magnetic disk322, which is inserted into the optical disk drive 305 or the magneticdisk drive 306, and transmitted to the hard disk 314. Alternatively, theprogram is transmitted via a network (not shown) to the computer system300 and stored in the hard disk 314. At the time of execution, theprogram is loaded into the RAM 313. The program is loaded from theoptical disk 321 or the magnetic disk 322, or directly from a network.The program includes, in various embodiments, a cleaning program forperiodically cleaning chamber surfaces, wafer holding components and thelike, which has protective coatings or barriers to protect from plasmaexposure. In various embodiments, cleaning program is run afterdetection of yttrium or yttrium compounds that are generated asprotective coatings or barriers decay over time. In various embodiments,the detection occurs during operation of the processing system 100. Invarious embodiments, the cleaning program is run during a maintenanceperiod when the processing system 100 is not operating.

The stored programs do not necessarily have to include, for example, anoperating system (OS) or a third party program to cause the computer 301to execute the methods disclosed herein. The program only includes acommand portion to call an appropriate function (module) in a controlledmode and obtain desired results in some embodiments. In variousembodiments described herein, the controller 300 is in communicationwith the processing system 100 to control various functions thereof. Invarious embodiments, the controller 300 automatically directs when tostart and/or stop a cleaning process, for example, when contaminants aredetected within the processing system 100.

The controller 300 is coupled to the chamber 120, monitoring device 215,upper assembly 220, substrate holder 240, pressure control system 250,control source 262, temperature control unit 265, gas supply system (gasdistribution system) 270, first RF or microwave source 124, second RFsource 285, and gate valve 290. The controller 300 is configured toprovide control data to those system components and receive processand/or status data from those system components. For example, thecontroller 300 includes a microprocessor, a memory (e.g., volatile ornon-volatile memory), and a digital I/O port capable of generatingcontrol voltages sufficient to communicate and activate inputs to theprocessing system 100, as well as monitor outputs from the processingsystem 100. Moreover, the controller 300 exchanges information withchamber 120, monitoring device 215, upper assembly 220, substrate holder240, pressure control system 250, control source 262, temperaturecontrol unit 265, gas supply system 270, first RF source 124, second RFsource 285, and gate valve 290 in some embodiments. In addition, in someembodiments, a program stored in the memory is utilized to control theaforementioned components of a processing system 100 according to aprocess recipe. Furthermore, the controller 300 is configured to analyzethe process and/or status data, to compare the process and/or statusdata with target process and/or status data, and to use the comparisonto change a process and/or control a system component. In addition, thecontroller 300 is configured to analyze the process and/or status data,to compare the process and/or status data with historical process and/orstatus data, and to use the comparison to predict, prevent, and/ordeclare a fault or alarm.

It has been found that with aluminum-based coatings used insemiconductor fabrication devices, yttrium particle accumulation occursfrom aging parts and tools, especially after fifteen hundred RF-hours ofplasma exposure time. Such particle accumulation has been discovered toarise from a fragile layer of yttrium-containing compounds that build upover time on a surface of the protective coating of such parts andtools. Such fragile layer, referred to herein as a peeling weaknesssurface (PWS), cannot be removed by prior cleaning processes, asdescribed previously above. The components include, but are not limitedto exhaust plates, bottom rings, deposition shields, shutters,deposition rings and the like. In various embodiments, the body of suchcomponents and chamber surfaces is made of aluminum. The surfaces ofsuch aluminum-based components are protected by a protective or surfacecoating that includes CO₂ and yttrium based compounds, such as Y₂O₃ orYF₃. Initially, such a protective coating protects the components fromdecay without impacting the composition and distribution of plasma 136within the plasma chamber 120. However, such coatings will age andgenerate contaminant particles during exposure to plasma after a periodof operation.

The Y₂O₃ coating found in processing chambers themselves (i.e. chamberwalls) is usually very stable to ambient conditions and has very highmelting temperature, namely up to two hundred sixty-eight degreesCelsius. However, under HBr/O₂ high density plasma conditions, OH ionsor hydrogen (H) and oxygen (O) atoms are generated. These species reactwith Y₂O₃ to form Y(OH)₃ as follows: Y₂O₃+3H₂O=2Y(OH)₃. This yttriumhydroxide is very brittle and forms airborne contaminant particles fromthe Y₂O₃ coating surface. After plasma etching or other processes usinga plasma 136, coated FC parts also age to form YOF, which in turn causesthe formation of a PWS layer 163 that generates excessive yttriumelement peeling and airborne contaminant particles 502 during plasmaexposure, as now described below.

FIG. 5 depicts plasma impact on a surface coating 132 of plasmaprocessing parts and tools (i.e., FC parts) over time according tovarious embodiments, where the surface coating is YO_(x)F_(y). In theoperation of some plasma chambers, mixed high-frequency (HF) andlow-frequency (LF) power conditions are employed. As shown in graph 500,the etch amount on a substrate 116 increases with the addition of LFpower. Namely, at four hundred watts (W) of HF and 0 W of LF (i.e., afirst condition in which HF is used but LF is not), the etch amount isabout thirty nanometers (nm). In this first condition, the surfacedamage is less than that of mixed RF conditions, however, a higherquantity of contaminant particles 502 may fall on the substrate. Thecontaminant particles 502 that drift from the PWS layer 163 generatedover time on the surface coating 132 therefore causes contamination ofthe substrate 116 during wafer processing. At 400 W of HF and 400 W ofLF (i.e., a second condition with mixed HF and LF usage), on the otherhand, the etch amount is about fifty nm. Concomitantly, such a mixedpower condition has higher parts damage that yields a low yttriumparticle count. The plasma sheath 504 generated within the plasmaprocessing chamber 120 protects from some drift of yttrium particlecontaminants, but such contaminant particles 502 are not completelycontained. Contaminant particles 502 do not fall on the substrate, as inthe first condition, but instead are directed back to the PWS layer 163,creating more severe surface damage on the FC parts. Plasma etchingusing high power trim will thus deteriorate the surface coating 132 ofFC parts after a sufficient period of high RF time. In aluminum toolswith yttrium-based surface coatings exposed to the plasma 136, thiscauses an yttrium particle source defect. There are also full-spectrumdefects in the yttrium-coated parts of the plasma etching chamber.

Yttrium-based coatings, such as Y₂O₃ coatings, have been used in plasmaprocess tools as a coating material due to its high resistance toerosion and corrosion, especially in metal or gate etch processes whichinvolve NF₃, Cl₂/O₂ or HBr/O₂ plasmas. However, in some processes,particles originating from Y₂O₃ coatings are increasingly problematic,especially as the lines and structures of manufactured semiconductordevices become smaller and smaller. These particles cause device andprocess failure. YF₃ coating is used instead of Y₂O₃ in an attempt tosuppress the generation of contaminant particles. However it has beenfound that the etch rate drifts or decreases significantly with fresh orcleaned parts, and extended dummy runs are required to season the partsin order to have an acceptable and stable etch rate. Contamination isalso generated from an unexpected source. FIG. 6 schematicallyillustrates the progression of the development of a PWS layer 163 on asurface coating 132 comprising YF₃ according to some embodiments. WhenFC parts are new or newly used (i.e., initial condition), the YF₃surface coating has no irregularities. It has been discovered that afterbeing exposed to plasma over a period of time, the surface of the YF₃coating slowly develops an irregular fragile PWS layer 163 ofYO_(x)F_(Y) through processes that are presently not well understood. Ithas been observed that this PWS layer 163 grows over time. As agingprogresses and plasma exposure continues, this PWS layer will generatecontaminant particles 502 that can be peeled off from the surface anddrift into the plasma chamber, thereby causing defects in workpieces.Wafer-less dry clean or wet clean processes are not sufficient toeliminate particle generation or to remove any portion of the PWS layer163.

Plasma etching with high power trim will consume parts after high RFtime due, at least in part, to fall-on particle residue. This, in turn,adversely affects the defect level of workpieces. FIG. 7 depict charts700 of three different defect levels of contaminant concentration overtime under partial etch conditions, according to some embodiments. Asshown in segment 710, an etch amount of seven nm is yielded after onehundred seventy hours of RF exposure. As shown in segment 720, thisyields an etch amount of residue in the amount of fourteen nm. As shownin segment 730, this results in a fall on contamination level of fivenm.

In some embodiments, the coated parts and Y-coated parts describedherein refer to FC parts. Examination of Y-coated parts in the plasmaprocessing chamber 120 by full spectra sensing found defects caused by Yparticle accumulation, originating from the fragile PWS layer 163 ofaging plasma processing parts after RF usage greater than fifteenhundred RF-hours. It has further been determined that such PWS layer 163cannot be effectively removed by standard cleaning operations.

In order to reduce the defect issue and achieve superior performance byand extended lifetime of plasma processing parts, an optimized etchamount of approximately ten nm is performed by embodiments of the newcleaning processes for such parts and tools as disclosed herein.Examination by a particle monitor, such as an XPS that searches for thespectral wavelength of Y, shows that the weaker bonding energy of thePWS layer 163 on plasma processing part surfaces is overcome by the newcleaning methods disclosed herein, and the altered PWS layer 163 thatyields Y contaminant particles is completely removed.

FIG. 8 illustrates the effects of the cleaning processes according toembodiments of the disclosure. A high-power fine-tuning process is usedto modify the plasma etching depth on a substrate 116. In someembodiments, more than fifteen hundred watts RF is employed. Thecleaning processes of the present disclosure is effective in removingthe weaker-bonding energy PWS layer 163 on plasma processing parts andtools. In particular, instead of a water washing, the cleaning processuses sand blasting. The “surface treatment” method of sand punching andcutting objects, also referred to herein as a sand blasting or a beadbeating method is a destructive processing method for removing anunwanted surface of the material. Fine abrasive sand particles or glassbeads are used to impact the surface of the material, so that thesurface produces a grain-like depression, thereby forming a mattesurface or an eroded surface. Bead beating is used in embodiments of thedisclosure as a new method to treat plasma processing parts in a mannernot heretofore contemplated. In various embodiments, a bead beatingapparatus includes a compressor (not shown) for supplying compressedair, a tank which contains an abrasive (not shown) to be used for thebead beating, a mixer that mixes the abrasive, as supplied from, forexample, an external supply pipe (not shown) with the compressed airsupplied from the compressor, and a nozzle (not shown) which sprays theabrasive from the mixer onto the surface of the material using thecompressed air. In some embodiments, the compressed air includes acarrier fluid the carrier fluid, for example, CDA (clean dry air),nitrogen, argon, and other suitable fluids. In some embodiments, theabrasive includes glass beads, sand or other suitable particulates ofappropriate size in the range of 1-5 nm.

After a certain number of bead beating operations, or a certain amountof time, the abrasive is removed after use by a vacuum pump and filteredto remove impurities and contaminants and reused in a subsequent beadbeating operation.

Diagram 800 of FIG. 8 displays the effects of the improved cleaningprocess on a protective coating or surface layer 132 on plasmaprocessing components, parts and tools. Segment 801 shows a surfacelayer 132 with a PWS layer 163 that generates contaminant particles 502after extended exposure to RF and plasma and before any cleaning processis applied. Segment 802 displays the effects of wet cleaning processeson the surface layer 132, in which the PWS layer 163 and contaminantparticles 502 are partially mitigated but largely remain. Segment 803displays the results of the bead beating process applied to the surfacelayer 132 in which the PWS layer 163 is largely removed and thegeneration of airborne contaminants is minimized.

Chart 900 of FIG. 9 further illustrates the difference in efficacybetween a wet clean process and a bead beating process according to someembodiments. Segment 901 displays an initial condition of a protectivebarrier, such as surface layer 132, where the top line represents anamount of fluorine (F), the middle line represent the amount of yttriumand the bottom line represents an amount of oxygen (O) present. Segment902 shows the composition of the same surface layer 132 after 2600 hoursof RF and plasma exposure followed by a wet clean process, in whichelevated amounts of Y and F are observed to remain. Segment 903 showsthe results of a beat beating clean process on the surface layer 132also performed after 2600 hours of RF and plasma exposure, in which thelevels of F, Y and O have been comparatively restored to their initialconditions and stabilized due to the PWS layer 163 being largelyremoved.

FIG. 10 is a chart illustrating the condition of the PWS layer 163 overtime and after cleaning according to some embodiments. As shown insegment 1001, which represents the characteristics of the surface layer132 after bead beating is applied, in-line defects improve 36%-50% belowthe average (shown by the dotted line) and the peek highs observed inprevious cycles are eliminated.

FIG. 11 shows a second chart 1100 illustrating the characteristics ofthe PWS layer 163 after cleaning and then after additional exposure toRF and plasma during wafer manufacturing operations, according tovarious embodiments. As demonstrated above, the bead beating cleaningprocesses restore the surface layer 132 to the initial operatingconditions (as illustrated by segment 1101), but over time, the depthand roughness of the surface layer 132 increases again with increased RFand plasma exposure (as illustrated in segment 1102). This will lead tomore airborne contaminant particles over time and the bead beatingcleaning process will need to be applied again.

FIG. 12 depicts a chart 1200 of coating thickness and roughness afterthe bead beating cleaning processes are applied, according to variousembodiments. Segment 1210 shows the initial thickness (in micrometers)of a typical PWS layer 163 after plasma exposure, where the thicknesscontrol limit is 110 μm. Segment 1220 shows roughness data the peelingweakness surface. Each application of the bead beating process removesabout 10 micrometers (um) of the PWS surface layer 132. In someembodiments, the thickness control limit of the surface layer 132 isbetween 110 um and 150 um. In some embodiments, the bead beating processis safely employed up to three times during the lifecycle of the part torevitalize the protective surface layer 132 without eliminating too muchof its depth. After one CoA cleaning, the data on the surface of theobject was measured by x-ray photoelectron spectroscopy (XPS). Segment1220 shows the thickness result from one such cleaning and demonstratesthat the coating depth remains within specifications. Segment 1230 showsthat roughness of the surface layer caused by buildup of the PWS layer163 over time is likewise returned to specification.

FIG. 13 is a flowchart of a process 1300 for detecting a PWS conditionand initiating a cleaning and revitalizing process in accordance withthe embodiments disclosed herein. At operation 1302, during a wafermanufacturing process, a sensor, such as sensor 299 monitors the plasmaprocessing chamber for airborne particle contamination. In someembodiments, this operation is performed when the processing system 100is offline in addition to or instead of being performed during theprocessing system operation.

At operation 1304, the controller 300 determines whether sufficientcontamination levels are present based on the readings of sensor 299 torequire cleaning contamination. In various embodiments, any detectableamount of airborne yttrium contamination particles 502 justifiescleaning. If particle contamination remains below a threshold value, theprocess 1300 continues to operation 1306. If contamination levels at orabove the threshold value are instead detected, the process 1300continues to operation 1310.

At operation 1306, the sensor 299 is used to monitor the thicknessand/or roughness of the PWS layer 163 on any plasma processing parts,tools or components within the processing chamber 120. At operation1308, the controller 300, based on the measurements from the sensor 299,determines whether a threshold amount of thickness or roughness ispresent on the plasma processing parts, tools and components to justifyan alarm condition. In various embodiments, the thickness threshold is10 um.

At operation 1310, the controller 300 generates an alarm condition inresponse to threshold levels of contamination present within the plasmaprocessing chamber 120. In response to the alarm condition, when theprocessing system is online, the wafer manufacturing process is haltedat operation 1312.

Next, at operation 1314, a bead beating cleaning process is initiated toremove the PWS layer 163 from the surface layer 132 on plasma processingparts, tools and components. In some embodiments, the bead beatingcleaning process is performed as a clean-in-place (CIP) process wherethe parts, tools or components are left in place in the processingsystem 100 while the cleaning process is performed. In such embodiments,after the cleaning process is performed, vacuum pumps and the like areused to remove any loose residue generated by the cleaning process formthe plasma processing chamber 120 before it is placed back intooperation. In other embodiments, the plasma processing parts, tools andcomponents are removed from the processing system 100 for cleaning andthen re-placed back in the plasma processing chamber 120 beforeoperation is re-commenced.

Then, at operation 1316, the sensor 299 is used to confirm removal ofsufficient depth of the PWS layer 163, and that the thickness and/orroughness of the surface layer 132 is within specifications. If so, theprocess returns to operation 1302 above and semiconductor processingoperations are resumed by the processing system 100. In variousembodiments, the sensor 299 performs its operation during processing,during bead blast cleaning, after cleaning, during an offline time ofthe processing system 100, and inside or outside of the plasmaprocessing chamber 120.

Benefits of the present disclosure include the removal of a PWS layerfrom tools and components that were not affected by wet clean methods.In various embodiments, the PWS layer is completely removed with eachapplication. At the same time, the protective surface coatings of thetools and components are preserved. This in turn allows the tools andcomponents to be used for extended lifetime when compared to the sametools and components not so cleaned. The cleaning of the PWS layer 163in the embodiments described herein further prevent contamination ofwafer processing equipment and workpieces, which, in turn, increasesproduction yields and reduces the downtime of such equipment.

According to various embodiments hereinabove, a method for cleaningcomponents of a plasma processing apparatus includes: (1) disposing awafer holding tool having a surface coating 132 within a chamber 120 ofthe plasma processing apparatus 100; (2) initiating a wafermanufacturing process; (3) detecting, by a sensor 299, a presence of anairborne contaminant within the chamber, the airborne contaminantoriginating from a peeling weakness surface (PWS) 163 on the surfacecoating 132; (4) halting the wafer manufacturing process; and (5)initiating a revitalizing process that removes a depth of the PWS 163from the surface coating 132.

In some embodiments, a thickness of the PWS 163 is measured afterinitiating the revitalizing process and when the thickness is within anacceptable range, the revitalizing process ends and the wafermanufacturing process is resumed. In some embodiments, a roughness ofthe PWS 163 is measured after initiating the revitalizing process andwhen the roughness is within an acceptable range, the revitalizingprocess ends and the wafer manufacturing process resumes. In someembodiments, the sensor 299 is activated after a threshold number ofhours of operation of the plasma processing apparatus 100. In someembodiments, the sensor 299 comprises an x-ray photoelectronspectroscopy sensor. In some embodiments, the plasma processingapparatus 100 is a plasma etching apparatus and the chamber is a plasmachamber. In some embodiments, the plasma processing apparatus 100 is aplasma deposition apparatus having a plasma generation stage includingthe chamber 120. In some embodiments, the PWS 163 is yttrium hydroxide.In some embodiments, the airborne contaminant comprises yttrium. In someembodiments, a depth of the PWS 163 removed is at least 10 micrometers.In some embodiments, the cleaning process is a bead beating process or asandblasting process.

In various embodiments, a method for prolonging the life of plasmaprocessing tools, parts and components includes: (1) disposing a waferholding tool within a chamber 120 of a plasma processing apparatus 100;(2) initiating a wafer manufacturing process; and (3) disposing a sensor299 within the chamber 120 for measuring a thickness of a peelingweakness surface 163 on a coating 132 of the wafer holding tool. Whenthe thickness exceeds a threshold value the wafer manufacturing processis halted and a revitalizing process for removing at least a portion ofthe peeling weakness surface 163 from the coating 132 is initiated.

In some embodiments, at least one of a depth and a roughness of thepeeling weakness surface 163 is measured and when the at least one ofthe depth and the roughness is within an acceptable range therevitalizing process ends and the wafer manufacturing process commences.In some embodiments, at most ten micrometers of a thickness of thepeeling weakness surface is removed from the coating. In someembodiments, the wafer manufacturing process is at least one of a plasmadeposition process and a plasma etching process. In some embodiments,the revitalizing process is a bead blasting process.

In various embodiments, a plasma processing method includes measuring atleast one of: (i) a thickness of a peeling weakness layer 163 on asurface coating 132 of the wafer holding tool, and (ii) a level ofairborne contaminant within the chamber 120. A revitalization process toremove substantially all of the peeling weakness layer 163 from thesurface coating 132 using bead beating is initiated when at least oneof: (i) the thickness of the depleted layer exceeds a thresholdthickness value, and (ii) an airborne contaminant originating from thePWS layer 163 is detected.

In some embodiments, the revitalization process is a CIP process. Insome embodiments, the wafer holding tool is at least one of a bottomring, an exhaust plate, a deposition shield, a shutter and a depositionring. In some embodiments, the wafer holding tool is aluminum and thesurface coating 132 is at least one of Y₂O₃ and YF₃.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method comprising: disposing a wafer holdingtool having a surface coating within a chamber of a plasma processingapparatus; initiating a wafer manufacturing process; detecting, by asensor, a presence of an airborne contaminant within the chamber, theairborne contaminant originating from a peeling weakness surface (PWS)on the surface coating; halting the wafer manufacturing process; andinitiating a revitalizing process that removes a depth of the PWS fromthe surface coating.
 2. The method of claim 1, further comprising:measuring a thickness of the PWS after initiating the revitalizingprocess; and when the thickness is within an acceptable range: endingthe revitalizing process; and resuming the wafer manufacturing process.3. The method of claim 1, further comprising: measuring a roughness ofthe PWS after initiating the revitalizing process; and when theroughness is within an acceptable range: ending the revitalizingprocess; and resuming the wafer manufacturing process.
 4. The method ofclaim 1, wherein the sensor is activated after a threshold number ofhours of operation of the plasma processing apparatus.
 5. The method ofclaim 1, wherein the plasma processing apparatus comprises a plasmaetching apparatus and the chamber comprises a plasma chamber.
 6. Themethod of claim 1, wherein the plasma processing apparatus comprises aplasma deposition apparatus having a plasma generation stage includingthe chamber.
 7. The method of claim 1, wherein the sensor comprises anx-ray photoelectron spectroscopy (XPS) sensor.
 8. The method of claim 1,wherein the PWS comprises yttrium hydroxide (YOH).
 9. The method ofclaim 1, wherein the airborne contaminant comprises yttrium (Y),
 10. Themethod of claim 1, wherein the depth of the PWS removed is at least 10micrometers.
 11. The method of claim 1, wherein the revitalizationprocess is a bead beating process.
 12. A method comprising: disposing awafer holding tool within a chamber of a plasma processing apparatus;initiating a wafer manufacturing process; measuring a thickness of apeeling weakness surface on a coating of the wafer holding tool using asensor disposed in the chamber; when the thickness exceeds a thresholdvalue: halting the wafer manufacturing process; and initiating arevitalizing process for removing at least a portion of the peelingweakness surface from the coating.
 13. The method of claim 12, furthercomprising: measuring at least one of a depth and a roughness of thepeeling weakness surface; and when the at least one of the depth and theroughness is within an acceptable range: ending the revitalizingprocess; and resuming the wafer manufacturing process.
 14. The method ofclaim 12, wherein at most 10 micrometers of a thickness of the peelingweakness surface is removed from the coating.
 15. The method of claim12, wherein the wafer manufacturing process comprises at least one of aplasma deposition process and a plasma etching process.
 16. The methodof claim 12, wherein the revitalizing process comprises a bead blastingprocess.
 17. A method, comprising: measuring at least one of: athickness of a peeling weakness layer on a surface coating of the waferholding tool, and a level of airborne contaminant within the chamber;and initiating a revitalization process that removes substantially allof the peeling weakness layer from the surface of the coating using beadbeating when at least one of: the thickness of the peeling weaknesslayer exceeds a threshold thickness value, and an airborne contaminantamount greater than a threshold limit is detected.
 18. The method ofclaim 17, wherein the revitalization process comprises a clean-in-place(CIP) process.
 19. The method of claim 17, wherein the wafer holdingtool comprises at least one of a bottom ring, an exhaust plate, adeposition shield, a shutter and a deposition ring.
 20. The method ofclaim 17, wherein the wafer holding tool comprises aluminum and thesurface coating comprises at least one of Y₂O₃ and YF₃.